Higher proportions of a healthy gastric mucosa in healthy Japanese adults with later birth year: analysis of 41 957 participants.

Background: In Japan, most gastric cancers are associated with gastric mucosal atrophy caused by chronic infection with Helicobacter pylori (H. pylori). Recognizing the condition of the gastric mucosa and determining the infection status of H. pylori are important for predicting the individual risk of gastric cancer. This study aimed to determine the proportion of Japanese adults with a healthy gastric mucosa (without H. pylori infection) among 12 birth-year groups encompassing 1935-1990 by morphological images.

Methods: The gastric mucosa was classified as healthy or having gastritis based on routine double-contrast upper gastrointestinal barium X-ray radiography. The participants included 41 957 healthy Japanese adults. Serum or urine H. pylori antibody levels were also assessed.

Results: In total, 25 424 participants had healthy mucosa without a history of H. pylori eradication. The proportions of participants with a healthy mucosa by birth year were 19.8% (57/288), 27.1% (306/1128), 32.4% (569/1756), 37.6% (1808/4811), 49.2% (3207/6522), 60.1% (3966/6550), 71.2% (5224/7342), 77.2% (5114/6624), 80.6% (3342/4149), 85.0% (1404/1652), 85.3% (302/354) and 94.7% (125/132) in 1935, 1940, 1945, 1950, 1955, 1960, 1965, 1970, 1975, 1980, 1985 and after 1990, respectively (P for trend <0.01). All the participants with a healthy mucosa showed negative results in the H. pylori antibody tests.

Conclusions: The proportion of participants with normal gastric mucosa linearly increased with the birth years. The prevalence of morphologically healthy gastric mucosa could have consistently increased with decreasing prevalence of H. pylori infection.